In 4th row there is a method called "Container.Content(parameter)"
which
Returns true if the current container you are in contains the following: files, songs, artists, albums, movies, tvshows, seasons, episodes, musicvideos, genres, years, actors, playlists, plugins, studios, directors....

But I don't know the name of parameter , so I can not pass that to get true or false.
instead I want to know the parameter/text/name (ex: files / songs /artists / albums etc) which the current container is containing.
how it can be done?

when you click on ".." in any window which is displaying songs or artists or albums , that takes you to the immediate parent list , now again click on ".." in that list to go one list above the current list.
This way you reach at one root level which does not display ".." entry , and displays icon of artists , albums , songs etc.
what is the name of this level?

Container.Content(what to pass here)
that it will return true when you are at this top level.